A 4- or 6-wheeled truck used in pairs under long-bodied railway vehicles. The bogie has a central pivot point which allows it to turn as the track curves and thus guide the vehicle into the curve. In the US it is always referred to as a truck. There are almost as many bogie designs as there are bogies. All-welded box-frame bogies with some steering capability are currently the fashion in Europe. Good design is crucial to good riding, although track condition is also very important in giving a good ride.